Musannaf Ibn Abi Shayba 3:2533

Abu Bakr narrated to us, he said: Umar bin Ayyub al-Mawsili narrated to us, from Ja'far bin Burqan, from Habib bin Abi Marzuq, from Amr bin Maymun, who said: Umar bin Abd al-Aziz asked him, "Do you count the verses during the prayer?" He replied, "I do not do so." He said, "And I also do not do so."